Method of producing the pointed end of a hypodermic needle



y 4, 1965 H. P. SCHOFIELD 3,181,336

METHOD OF PRODUCING THE POINTED END OF A HYPODERMIC NEEDLE Filed NOV.15, 1961 -F/G.6.- v, F/G.7.-'

23 2 22 I5 INVENTOR:

Huoe'm' P ScnaE'n-D United States Patent C) 3,131,336 METHGD @FFRQDUOING THE PQlNTED END @F A HYFODERMHE Hubert Percival Schoiield,Langdale, Hatchet Laue, Windsor Forest, England Filed Nov. 15, 196i,Ser. No. 152,558 2 Claims. (Cl. 72-34=dl The present invention relatesgenerally to the manufactors of hypodermic needles, and moreparticularly of the pointed ends thereof.

An object of this invention is to provide a method consisting ofinexpensive and easily practiced steps by which, starting from hollowtubing, hypodermic needles may be cheaply mass produced so as to eachhave a pointed end portion having at least one narrow slit openinglaterally from the axial bore of the tube or needle at the pointed endportion thereof.

Since the passage for emitting liquid from the hypodermic needle isrestricted to a narrow slit opening lateral- 1y from the bore of thetube at the tapering or pointed end portion thereof, there is nopossibility of the cutting of a disk or other shaped small piece of skinby the needle during penetration of the latter through the skin, andsuch penetration is effected by a piercing and spreading action, asdistinct from a cutting action.

In accordance with an aspect of this invention, the pointed end of ahypodermic needle is formed by flattening an end portion of an axiallybored hollow tube of deformable material to give such end portion atapering configuration leading to a point with at least one ear-likeprojection extending laterally therefrom and having two thicknesses ofthe material, and then trimming cit the projection so as to provide atleast one narrow slit opening laterally from the axial bore of the tubeat the tapering end portion of the latter.

In a preferred embodiment of the invention, the ear-like projectionextending laterally from one side of the tapering end portion of thetube is spaced along such end portion from the point of the latter sothat, after trimming off of the projection, the resulting slit is spacedfrom the point which is solid.

A further feature of the present invention resides in providing duringmanufacture of the needle a variable width of discharge orifice so as tocater for factors of injection such as viscosity of the liquid to beinjected, homogenisation, turbulence and resistance to liquid how.

The invention is more particularly described with reference to theaccompanying drawings which illustrate several forms of construction byway of example and in which:

FIGURE 1 is a longitudinal View of one end of a tubular element of oneembodiment in an intermediate stage of manufacture thereof.

FIGURE 2 is a similar longitudinal view but in a plane at right anglesto that of FIGURE 1 of the finished needle thereof.

FIGURE 3 is a section on the line EFL-ill of FIG- URE 1.

FIGURE 4 is a corresponding end view of the finished product.

FIGURE 5 is a longitudinal view of one end of a tubular element in anintermediate stage of manufacture of a modification.

FlGURE 6 is a longitudinal view in a plane normal to that of FIGURE 5 ofthe corresponding end of the finished needle.

FIGURE 7 is a section on the line VllVll of FIG- URE 5, and 7 FIGURE 8is a corresponding end view of the finished needle shown in FIGURE 6.

fidhl iidfi Fatented May 4, 1 .965

In the embodiment shown in FIGURES 13, the element to be made into atubular hypodermic needle is a tube 15 which may be of metal or again ofplastic and may be made by boring a solid wire in the case of a metal orby extrusion in the case of a plastic. That end of the hollow tube 15which is to constitute the pointed end of the needle is first flattenedto form cars 16, 1'7 and to take the form of a spear whereupon it istrimmed to a point and ground to a shape concentric about its axis ofsymmetry as shown in FIGURE 2 so that the ears disappear and theopposite faces of the tube are separated to form leaves l8, 19 whichtaper to what is virtually a sharp point 2% leaving an extremely narrowslit 21 between them through which liquid is forced during use of theneedle; in the case of a small needle this slit which extendslongitudinally of the needle may be as small as a few thousandths of aninch in width, so much so that it cannot function in the cutting orsevering of skin, with the result that a piercing as distinct from acutting operation is performed on passage of the neeedle point throughthe skin.

In other words it is impossible during use of the needle for any part ofthe skin to be wholly severed at the site of puncture and for thesolution being injected to drag with it any foreign matter into anopening of the skin made by the pointed end of the needle 15.

It will be appreciated that, by virtue of the substantially angularcross-sectional shape of the ears l6, 17 as shown in FIGURE 3, the widthof each slit will depend on the extent of the final grinding operationin completing the removal of the ears 7.6, 17, that is to say thegreater the depth of grind the wider the slits and vice versa, so as tocater for factors of liquid viscosity, resistance to liquid flow,homogenisation and turbulence and the like at the needle orifice duringinjection.

The two leaves l8, 19 may take any desired shape, that is to say theymay be substantially flat, or again they may be slightly convex orconcave in form to impart strength for resisting any tendency for themto spread open during the entry of the tip Zll into flesh or muscle. itwill be appreciated, however, that this embodiment could be formed withthree, four or even more leaves.

In the construction illustrated in FIGURES 58 a single car 22 is formedon one side only of the tube and is cut oil either in the same or asubsequent operation to leave a narrow longitudinal slit 23 on one sideonly of the tubular needle. In this form of construction, as with thatof FIGURES 1-4, the final step in the manufacture of the tube is the actof grinding it to its finished concentric form and the pointed end isindeed solid as shown at 2d. The same remarks apply to thewidth of theslit 23 as with that of each slit 21 in the construction according toFIGURES 14.

Any of the many known techniques utilised in the manufacture of pointedarticles such as needles may be employed in producing any of theembodiments or their alternatives.

As regards the opposite end of the needle, in one form of constructionthe needle may be produced complete with connector or ferrule, i.e. withthe whole formed or assembled in one piece of metal, if necessary usingknown techniques not previously considered for this application.

In another form that end of the needle remote from the point or tip maybe spread, upset, or dimpled to provide a suitable key for fixing in aplastic ferrule or socket, which may be injection moulded direct on tothe needle. Nylon, Rilsan, or the like plastic is suitable for use wherethe needle is to undergo heat sterilization, but when cold sterilizationis required, cheaper plastics such as polystyrene or polythene may beused.

Apart from overcoming the disadvantages of the conventional hypodermicneedle both as regards manufacture and use, needlesof the presentinvention may be manufactured and sold at a much cheaper price, therebyenabling each to be economically disposable after one use; in thisrespect it is my experience that once a needle has been used, the borecan never be satisfactorily cleaned, and although it can be sterilisedthedanger always exists of injecting sterile foreignmatter from onepatient to another. This applies to the syringe to which it may befitted.

In the foregoing the invention has been described with reference tospecific illustrative devices. It will be evident, howeyer, thatvariations and modifications may be made without departing from thebroader scope and spirit of the invention as set forth in the appendedclaims. The specification and drawings are accordingly to be regarded inan illustrative rather than in a restrictive sense.

I claim:

1.. A method of producing the pointed end of a hypodermic needlecomprising flattening an end portion of an axially bored hollow tube. ofdeformable material to give said end portion a tapering configurationleading to a solid point with one ear-like projection extendinglaterally from one side of said tapering end portion and having twothicknesses of said material, and trimming-01f said projection so as toprovide one narrow slit opening lateral- 2 1y from the axial bore of thetube at the tapering end portion of the tube inback of said solid point.

4 2. The method as in claim 1; wherein the two thicknesses of materialof said ear-lik projection diverge slightly toward the axis of said tubeso that the width of said slit is dependent upon the extent to whichsaid ear-like projection is trimmed-ofit.

creases Cited by the Examiner UNITED STATES PATENTS 1,731,867 10/29 Rice29-543 X 2,032,991 3/36 Lange 29539 X 2,130,173 9/38 Barnes. 2,133,09210/38 Gettig 29537 2,213,098 8/40 Smith 113-32 X 2,511,858 6/50 Lampton113-52 X 2,634,726 4/53 Hanson 128--221 2,737,948 3/56 Brown 128-221X2,746,455 5/56 Abel 128221 2,954,768 10/60 Hamilton 128--221 2,989,0536/61 Hamilton 128-22l FOREZGN PATENTS 1,196,601 11/59 France.

630,377 10/49 Great Britain.

WHITMORE A. WILTZ,-Primary Examiner.

RICHARD J. HOFFMAN, Examiner.

1. A METHOD OF PRODUCING THE POINTED END OF A HYPODERMIC NEEDLECOMPRISING FLATTENING AN END PORTION OF AN AXIALLY BORED HOLLOW TUBE OFDEFORMABLE MATERIAL TO GIVE SAID END PORTION A TAPERING CONFIGURATIONLEADING TO A SOLID POINT WITH ONE EAR-LIKE PROJECTION EXTENDINGLATERALLY FROM ONE SIDE OF SAID TAPERING END PORTION AND HAVING TWOTHICKNESSES OF SAID MATERIAL, AND TRIMMING-OFF SAID PROJECTION SO AS TOPROVIDE ONE NARROW SLIT OPENING LATERALLY FROM THE AXIAL BORE OF THETUBE AT THE TAPERING END PORTION OF THE TUBE IN BACK OF SAID SOLIDPOINT.